1. (a) Field of the Invention
The present invention relates to a plasma display and a driving apparatus thereof.
2. (b) Description of the Related Art
A plasma display includes a display panel having a plurality of display electrodes and a plurality of discharge cells defined by the display electrodes. The display electrodes, for example, include address electrodes, scan electrodes and sustain electrodes. The plasma display displays an image by applying a sustain pulse having a high level voltage and a low level voltage alternately to a pair of display electrodes (e.g., sustain electrodes) to perform a sustain discharge for sustain-discharging a cell that is defined by the pair of display electrodes to emit light. Hereinafter, the cell will be referred to as a light emitting cell. Since a capacitive component (hereinafter referred to as “a panel capacitor”) is formed by the pair of display electrodes where the sustain discharge is generated, a reactive power is generated when the high level voltage and the low level voltage are respectively applied to the pair of display electrodes. For example, to improve power efficiency or reduce power consumption, a typical plasma display may include an energy recovery circuit for reusing (or recovering) the reactive power.
The energy recovery circuit includes an energy recovery capacitor and an inductor that is electrically coupled between a panel capacitor and the energy recovery capacitor. The energy recovery circuit generates a resonance between the inductor and the panel capacitor, recovers a resonant current corresponding to a discharge in the panel capacitor to the energy recovery capacitor, and supplies the resonant current for charging the panel capacitor from the energy recovery capacitor. In order to increase the capacitance of the energy recovery capacitor, a plurality of capacitors, each having the same capacitance and coupled in parallel, may be used as the energy recovery capacitor.
However, a variation (e.g., capacitance, parasitic inductance) may exist between the plurality of capacitors coupled in parallel, or a variation may exist between parasitic inductive components that may be represented as inductors respectively coupled to the plurality of capacitors in series.
When a variation exists between the plurality of capacitors, for example between a first capacitor and a second capacitor, a resonance cycle (i.e., an inverse number of a resonance frequency) of the first capacitor and the inductor is different from a resonance cycle of the second capacitor and the inductor so that the amount of current flowing to the first capacitor and the amount of current flowing to the second capacitor may differ from each other at the end of their resonance cycles. Then, a resonance is generated again through a closed loop that is formed by the first capacitor, the parasitic inductive component coupled to the first capacitor, the second capacitor, and the parasitic inductive component coupled to the second capacitor so that a resonance current may flow through the closed loop. Even when the first and second capacitors have the same capacitance, the parasitic inductive component coupled to the first capacitor and the parasitic inductive component coupled to the second capacitor may have different inductances. In this case, the resonance cycle corresponding to the first capacitor and the inductor, and the resonance cycle corresponding to the second capacitor and the inductor become different from each other due to the variation of the parasitic inductive components so that the resonance may still occur through the closed loop.
While the resonance is being generated, the resonance cycle is proportional to a square root of the product of the capacitance of the capacitor and the inductance of the inductor in the resonance path. However, the capacitance of each of the first and second capacitors is set (or configured) to be larger than that of the panel capacitor, and the inductance of the inductor is set (or configured) to be larger than that of the parasitic inductive component in the energy recovery circuit. Therefore, a resonance cycle formed by the first and second capacitors and their parasitic inductive components in the closed loop may be similar to a resonance cycle formed by the panel capacitor and the inductor.
Therefore, the resonance current in the closed loop may reach a maximum value during a period in which the high level voltage or the low level voltage is applied (i.e., maintained) to the display electrode. Accordingly, a large resonance current is repeatedly supplied to the first and second capacitors while the period is repeated so that temperatures of the first and second capacitors may increase, thereby causing overheating of the energy recovery circuit or degradation of the first and second capacitors.